Please enlighten anyone

which do you use :

Select * ;
from parent,child ;
where parent.key=child.key ;
into cursor temp

or

Select * ;
from parent ;
join child on parent.key=child.key ;
into cursor temp

Can anyone recommend a very good book on the use of SQL-SELECT where there are very good or much better excellent examples on the use of nested select statements that span several child tables and span lookup tables in one SQL statement ???